Note: Descriptions are shown in the official language in which they were submitted.
CA 02831948 2013-11-01
=
MARINE ENGINE LUBRICATION
FIELD OF THE INVENTION
This invention relates to system oil lubrication of a two-stroke cross-head
marine
compression-ignited engine. This invention relates to a system oil for a two-
stroke cross-
head marine compression-ignited engine.
BACKGROUND OF THE INVENTION
Two-stroke marine diesel engines are compression-ignition engines in which
each
piston rod is connected to the crankshaft by a cross-head bearing. They are
lubricated by
two separate lubricants: cylinder oil and system oil. The cylinder oil is a
'once-through'
lubricant that is burnt in the combustion chamber, excess cylinder oil being
drained via
the cylinder oil duct. The crankcase of the engine is lubricated by the system
oil which
lubricates the bearings and journals as well as cooling the piston undercrown.
Due to the low stress placed upon it, the system oil is not changed. It needs
to be
able to cope with contamination arising from cylinder drain oil passing
through the
stuffing box; system oils blended with Group I base oils are able to cope with
this
contamination. However, higher saturate base oils (such as Group II) have been
shown to
be detrimental in respect of asphaltene dispersancy, which may deposit on the
undercrown of the pistons and on the crankcase. This constitutes a problem in
devising
system lubricants that are blended with higher saturate base oils.
WO 2008/119936 Al (`936) describes system lubrication and mentions Group I
and Group II basestocks for system oils. It also describes use of calcium
alkyl salicylate
detergents soap in a system oil. It does not, however, exemplify use of Group
II
basestocks nor does it mention the above problem regarding Group II
basestocks.
CA 02831948 2013-11-01
,
SUMMARY OF THE INVENTION
The invention is concerned with ameliorating the above problem by
incorporating
a polyalkenyl-substituted carboxylic acid anhydride or an alkylated phenol in
a salicylate-
containing system oil blended with a higher saturates basestock. Use of such
anhydrides
or phenols is not described in '936. WO 2008/021737 A2 (`737) describes use of
such
anhydrides in marine lubricants, but does not mention system lubrication. It
mentions
salicylate detergents but exemplifies only sulphonate/phenate detergents.
A first aspect of the invention is a system lubricating oil composition (i.e.
a
system oil) for a two-stroke cross-head marine compression-ignited engine, the
composition having a TBN of less than 18, preferably less than 15, preferably
5 to 9, and
comprising, or being made by admixing:
(A) an oil of lubricating viscosity, in a major amount, containing 50 mass% or
more of a basestock containing greater than or equal to 90% saturates and less
than or equal to 0.03% sulphur or a mixture thereof;
(B) an oil-soluble overbased metal alkyl salicylate detergent, in a minor
amount;
and
(C) in a minor amount, an oil-soluble polyalkenyl-substituted carboxylic acid
anhydride, the, or at least one, polyalkenyl group being derived from a
polyalkene
having a number average molecular weight of from 200 to 3,000, or an oil-
soluble
alkylated phenol, preferably an oil-soluble alkylated phenol derived from
cashew
nut shell liquid (CNSL).
A second aspect of the invention is a method of providing system lubrication
to a
two-stroke cross-head marine compression-ignited engine, which comprises
lubricating
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CA 02831948 2013-11-01
the crankcase of the engine with a system lubricating oil composition of the
first aspect of
the invention.
A third aspect of the invention is a combination of the crankcase of a two-
stroke
cross-head marine compression-ignited engine and a system lubricating oil
composition
of the first aspect of the invention.
A fourth aspect of the invention is the use of detergent (B) as defined in the
first
aspect of the invention in combination with a polyalkenyl-substituted
carboxylic acid
anhydride or alkylated phenol (C) as defined in the first aspect of the
invention in
respective minor amounts in a system lubricating oil composition for a two-
stroke cross-
head marine compression-ignited engine, which composition comprises an oil of
lubricating viscosity in a major amount and contains 50 mass % or more of a
basestock
containing greater than or equal to 90% saturates and less than or equal to
0.03% sulphur
or a mixture thereof, to improve asphaltene dispersancy during operation of
the engine,
fueled by a heavy fuel oil, and its system lubrication by the composition, in
comparison
with analogous operation when the same amount of (B) is used in the absence of
(C).
In this specification, the following words and expressions, if and when used,
have
the meanings ascribed below:
"active ingredients" or "(a.i.)" refers to additive material that is not
diluent or
solvent;
"comprising" or any cognate word specifies the presence of stated features,
steps,
or integers or components, but does not preclude the presence or addition of
one
or more other features, steps, integers, components or groups thereof; the
expressions "consists of' or "consists essentially of" or cognates may be
embraced within "comprises" or cognates, wherein "consists essentially of'
permits inclusion of substances not materially affecting the characteristics
of the
composition to which it applies;
3
CA 02831948 2013-11-01
,
,
,
"major amount" means 50 mass % or more of a composition;
"minor amount" means less than 50 mass % of a composition;
"TBN" means total base number as measured by ASTM D2896.
Furthermore in this specification, if and when used:
"calcium content" is as measured by ASTM 4951;
"phosphorus content" is as measured by ASTM D5185;
"sulphated ash content" is as measured by ASTM D874;
"sulphur content" is as measured by ASTM D2622;
"KV100" means kinematic viscosity at 100 C as measured by ASTM D445.
Also, it will be understood that various components used, essential as well as
optimal and customary, may react under conditions of formulation, storage or
use and
that the invention also provides the product obtainable or obtained as a
result of any such
reaction.
Further, it is understood that any upper and lower quantity, range and ratio
limits
set forth herein may be independently combined.
DETAILED DESCRIPTION OF THE INVENTION
The features of the invention will now be discussed in more detail below.
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OIL OF LUBRICATING VISCOSITY (A)
The lubricating oils may range in viscosity from light distillate mineral oils
to
heavy lubricating oils. Generally, the viscosity of the oil ranges from 2 to
40 mm2/sec, as
measured at 100 C.
Natural oils include animal oils and vegetable oils (e.g., castor oil, lard
oil); liquid
petroleum oils and hydrorefined, solvent-treated or acid-treated mineral oils
of the
paraffinic, naphthenic and mixed paraffinic-naphthenic types. Oils of
lubricating
viscosity derived from coal or shale also serve as useful base oils.
Synthetic lubricating oils include hydrocarbon oils and halo-substituted
hydrocarbon oils such as polymerized and interpolymerized olefins (e.g.,
polybutylenes,
polypropylenes, propylene-isobutylene copolymers, chlorinated polybutylenes,
poly(1-
hexenes), poly(1-octenes), poly(1-decenes)); alkybenzenes (e.g.,
dodecylbenzenes,
tetradecylbenzenes, dinonylbenzenes, di(2-ethylhexyl)benzenes); polyphenyls
(e.g.,
biphenyls, terphenyls, alkylated polyphenols); and alkylated diphenyl ethers
and
alkylated diphenyl sulphides and derivative, analogues and homologues thereof.
Alkylene oxide polymers and interpolymers and derivatives thereof where the
terminal hydroxyl groups have been modified by esterification, etherification,
etc.,
constitute another class of known synthetic lubricating oils. These are
exemplified by
polyoxyalkylene polymers prepared by polymerization of ethylene oxide or
propylene
oxide, and the alkyl and aryl ethers of polyoxyalkylene polymers (e.g., methyl-
polyiso-
propylene glycol ether having a molecular weight of 1000 or diphenyl ether of
poly-
ethylene glycol having a molecular weight of 1000 to 1500); and mono- and
polycarboxylic esters thereof, for example, the acetic acid esters, mixed C3-
C8 fatty acid
esters and C13 oxo acid diester of tetraethylene glycol.
Another suitable class of synthetic lubricating oils comprises the esters of
dicarboxylic acids (e.g., phthalic acid, succinic acid, alkyl succinic acids
and alkenyl
CA 02831948 2013-11-01
succinic acids, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric
acid, adipic
acid, linoleic acid dimer, malonic acid, alkylmalonic acids, alkenyl malonic
acids) with a
variety of alcohols (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-
ethylhexyl
alcohol, ethylene glycol, diethylene glycol monoether, propylene glycol).
Specific
examples of such esters includes dibutyl adipate, di(2-ethylhexyl) sebacate,
di-n-hexyl
fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl
phthalate,
didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl diester of linoleic
acid dimer, and
the complex ester formed by reacting one mole of sebacic acid with two moles
of
tetraethylene glycol and two moles of 2-ethylhexanoic acid.
Esters useful as synthetic oils also include those made from C5 to C12
monocarboxylic acids and polyols and polyol esters such as neopentyl glycol,
trimethylolpropane, pentaerythritol, dipentaerythritol and tripentaerythritol.
Silicon-based oils such as the polyalkyl-, polyaryl-, polyalkoxy- or
polyaryloxysilicone oils and silicate oils comprise another useful class of
synthetic
lubricants; such oils include tetraethyl silicate, tetraisopropyl silicate,
tetra-(2-
ethylhexyl)silicate, tetra-(4-methyl-2-ethylhexyl)silicate, tetra-(p-tert-
butyl-phenyl)
silicate, hexa-(4-methyl-2-ethylhexyl)disiloxane,
poly(methyl)siloxanes and
poly(methylphenyl)siloxanes. Other synthetic lubricating oils include liquid
esters of
phosphorus-containing acids (e.g., tricresyl phosphate, trioctyl phosphate,
diethyl ester of
decylphosphonic acid) and polymeric tetrahydrofurans.
Unrefined, refined and re-refined oils can be used in lubricants of the
present
invention. Unrefined oils are those obtained directly from a natural or
synthetic source
without further purification treatment. For example, a shale oil obtained
directly from
retorting operations; petroleum oil obtained directly from distillation; or
ester oil obtained
directly from esterification and used without further treatment, are unrefined
oils.
Refined oils are similar to unrefined oils except that the oil is further
treated in one or
more purification steps to improve one or more properties. Many such
purification
techniques, such as distillation, solvent extraction, acid or base extraction,
filtration and
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CA 02831948 2013-11-01
percolation, are known to those skilled in the art. Re-refined oils are
obtained by
processes similar to those used to provide refined oils but begin with oil
that has already
been used in service. Such re-refined oils are also known as reclaimed or
reprocessed
oils and are often subjected to additional processing using techniques for
removing spent
additives and oil breakdown products.
The American Petroleum Institute (API) publication "Engine Oil Licensing and
Certification System", Industry Services Department, Fourteenth Edition,
December
1996, Addendum 1, December 1998 categorizes base stocks as follows:
(a) Group I base stocks contain less than 90 percent saturates and/or
greater
than 0.03 percent sulphur and have a viscosity index greater than or equal
to 80 and less than 120 using the test methods specified in Table E-1.
(b) Group II base stocks contain greater than or equal to 90 percent
saturates
and less than or equal to 0.03 percent sulphur and have a viscosity index
greater than or equal to 80 and less than 120 using the test methods
specified in Table E-1.
(c) Group III base stocks contain greater than or equal to 90 percent
saturates
and less than or equal to 0.03 percent sulphur and have a viscosity index
greater than or equal to 120 using the test methods specified in Table E-1.
(d) Group IV base stocks are polyalphaolefins (PAO).
(e) Group V base stocks include all other base stocks not included in Group
I,
II, III, or IV.
Analytical Methods for Base Stock are tabulated below:
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TABLE E-1
PROPERTY TEST METHOD
Saturates ASTM D 2007
Viscosity Index ASTM D 2270
Sulphur ASTM D 2622
ASTM D 4294
ASTM D 4927
ASTM D 3120
By way of example, the present invention embraces Group II, Group III and
Group IV basestocks and also basestocks derived from hydrocarbons synthesised
by the
Fischer-Tropsch process. In the Fischer-Tropsch process, synthesis gas
containing carbon
monoxide and hydrogen (or `syngas') is first generated and then converted to
hydrocarbons using a Fischer-Tropsch catalyst. These hydrocarbons typically
require
further processing in order to be useful as a base oil. For example, they may,
by methods
known in the art, be hydroisomerized; hydrocracked and hydroisomerized;
dewaxed; or
hydroisomerized and dewaxed. The syngas may, for example, be made from gas
such as
natural gas or other gaseous hydrocarbons by steam reforming, when the
basestock may
be referred to as gas-to-liquid ("GTL") base oil; or from gasification of
biomass, when
the basestock may be referred to as biomass-to-liquid ("BTL" or "BMTL") base
oil; or
from gasification of coal, when the basestock may be referred to as coal-to-
liquid
("CTL") base oil.
As stated, the oil of lubricating viscosity in this invention contains 50 mass
% or
more of the defined basestock or a mixture thereof. Preferably, it contains
60, such as 70,
80 or 90, mass % or more of the defined basestock or a mixture thereof The oil
of
lubricating viscosity may be substantially all the defined basestock or a
mixture thereof
The basestock may for example be a Group II, Group III or Group IV basestock.
8
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METAL ALKYL SALICYLATE DETERGENT (B)
A metal detergent is an additive based on so-called metal "soaps", that is
metal
salts of acidic organic compounds, sometimes referred to as surfactants. They
generally
comprise a polar head with a long hydrophobic tail. Overbased metal
detergents, which
comprise neutralized metal detergents as the outer layer of a metal base (e.g.
carbonate)
micelle, may be provided by including large amounts of metal base by reacting
an excess
of a metal base, such as an oxide or hydroxide, with an acidic gas such as
carbon dioxide.
In the present invention, (B) is an overbased metal, such as calcium, alkyl-
substituted salicylate.
Such a detergent, where the metal is calcium, typically has the structure
shown:
/ OH
I¨C Ca2+
\Oy
wherein R is a linear alkyl group. There may be more than one R group attached
to the
benzene ring. The C00- group can be in the ortho, meta or para position.with
respect to
the hydroxyl group; the ortho position is preferred. The R group can be in the
ortho,
meta or para position with respect to the hydroxyl group.
Salicylic acids are typically prepared by the carboxylation, by the Kolbe-
Schmitt
process, of phenoxides, and in that case, will generally be obtained (normally
in a
diluent) in admixture with uncarboxylated phenol. Salicylic acids may be non-
sulphurized or sulphurized, and may be chemically modified and/or contain
additional
substituents. Processes for sulphurizing an alkyl salicylic acid are well
known to those
skilled in the art, and are described, for example, in US 2007/0027057.
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The alkyl groups advantageously contain 5 to 100, preferably 9 to 30,
especially
14 to 24, carbon atoms.
The term "overbased" is generally used to describe metal detergents in which
the
ratio of the number of equivalents of the metal moiety to the number of
equivalents of the
acid moiety is greater than one. The term low-based' is used to describe metal
detergents in which the equivalent ratio of metal moiety to acid moiety is
greater than 1,
and up to about 2.
By an "overbased calcium salt of surfactants" is meant an overbased detergent
in
which the metal cations of the oil-insoluble metal salt are essentially
calcium cations.
Small amounts of other cations may be present in the oil-insoluble metal salt,
but
typically at least 80, more typically at least 90, for example at least 95,
mole %, of the
cations in the oil-insoluble metal salt, are calcium ions. Cations other than
calcium may
be derived, for example, from the use in the manufacture of the overbased
detergent of a
surfactant salt in which the cation is a metal other than calcium. Preferably,
the metal salt
of the surfactant is also calcium.
Carbonated overbased metal detergents typically comprise amorphous
nanoparticles. Additionally, there are disclosures of nanoparticulate
materials comprising
carbonate in the crystalline calcite and vaterite forms.
The basicity of the detergents may be expressed as a total base number (TBN).
A
total base number is the amount of acid needed to neutralize all of the
basicity of the
overbased material. The TBN may be measured using ASTM standard D2896 or an
equivalent procedure. The detergent may have a low TBN (i.e. a TBN of less
than 50), a
medium TBN (i.e. a TBN of 50 to 150) or a high TBN (i.e. a TBN of greater than
150,
such as 150-500). The basicity may also be expressed as basicity index (BI)
which is the
molar ratio of total base to total soap in the overbased detergent.
CA 02831948 2013-11-01
The treat rate of additive (B) in the lubricating oil composition may for
example
be in the range of 0.1 to 10, preferably 0.5 to 9, more preferably 1 to 8,
even more
preferably 1-6, mass %.
POLYALKENYL-SUBSTITUTED CARBOXYLIC ACID ANHYDRIDE OR
ALKYLATED PHENOL (C)
The anhydride may be mono or polycarboxylic, preferably dicarboxylic. The
polyalkenyl group preferably has from 8 to 400, such as 8 to 100, carbon
atoms.
General formulae of exemplary anhydrides may be depicted as
R1
HC¨CO
H2C¨CO
where R1 represents a C8 to C100 branched or linear polyalkenyl group:
The polyalkenyl moiety may have a number average molecular weight of from
200 to 3000, preferably from 350 to 950.
Suitable hydrocarbons or polymers employed in the formation of the anhydrides
of the present invention to generate the polyalkenyl moieties include
homopolymers,
interpolymers or lower molecular weight hydrocarbons. One family of such
polymers
comprise polymers of ethylene and/or at least one C3 to C28 alpha-olefin
having the
formula H2C=CHR1 wherein R1 is straight or branched chain alkyl radical
comprising 1
to 26 carbon atoms and wherein the polymer contains carbon-to-carbon
unsaturation,
preferably a high degree of terminal ethenylidene unsaturation. Preferably,
such
polymers comprise interpolymers of ethylene and at least one alpha-olefin of
the above
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CA 02831948 2013-11-01
formula, wherein RI is alkyl of from 1 to 18 carbon atoms, and more preferably
is alkyl
of from 1 to 8 carbon atoms, and more preferably still of from 1 to 2 carbon
atoms.
Therefore, useful alpha-olefin monomers and comonomers include, for example,
propylene, butene-1, hexene-1, octene-1, 4-methylpentene-1, decene-1, dodecene-
1,
tridecene -1 , tetradecene-1, pentadecene-1, hexadecene-1, heptadecene-1,
octadecene-1,
nonadecene-1, and mixtures thereof (e.g., mixtures of propylene and butene-1,
and the
like).
Exemplary of such polymers are propylene homopolymers, butene-1
homopolymers, ethylene-propylene copolymers, ethylene-butene-1 copolymers,
propylene-butene copolymers and the like, wherein the polymer contains at
least some
terminal and/or internal unsaturation. Preferred polymers are unsaturated
copolymers of
ethylene and propylene and ethylene and butene-1. The interpolymers may
contain a
minor amount, e.g. 0.5 to 5 mole % of a C4 to C18 non-conjugated diolefin
comonomer.
However, it is preferred that the polymers comprise only alpha-olefin
homopolymers,
interpolymers of alpha-olefin comonomers and interpolymers of ethylene and
alpha-
olefin comonomers. The molar ethylene content of the polymers employed is
preferably
in the range of 0 to 80 %, and more preferably 0 to 60 %. When propylene
and/or
butene-1 are employed as comonomer(s) with ethylene, the ethylene content of
such
copolymers is most preferably between 15 and 50 %, although higher or lower
ethylene
contents may be present.
These polymers may be prepared by polymerizing alpha-olefin monomer, or
mixtures of alpha-olefin monomers, or mixtures comprising ethylene and at
least one C3
to C28 alpha-olefin monomer, in the presence of a catalyst system comprising
at least one
metallocene (e.g., a cyclopentadienyl-transition metal compound) and an
alumoxane
compound. Using this process, a polymer in which 95 % or more of the polymer
chains
possess terminal ethenylidene-type unsaturation can be provided. The
percentage of
polymer chains exhibiting terminal ethenylidene unsaturation may be determined
by
FTIR spectroscopic analysis, titration, or C13 NMR. Interpolymers of this
latter type may
be characterized by the formula POLY-C(R1)=CH2 wherein RI is CI to C26 alkyl,
preferably CI to C18 alkyl, more preferably CI to C8 alkyl, and most
preferably CI to C2
alkyl, (e.g., methyl or ethyl) and wherein POLY represents the polymer chain.
The chain
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CA 02831948 2013-11-01
length of the R1 alkyl group will vary depending on the comonomer(s) selected
for use in
the polymerization. A minor amount of the polymer chains can contain terminal
ethenyl,
i.e., vinyl, unsaturation, i.e. POLY-CH=CH2, and a portion of the polymers can
contain
internal monounsaturation, e.g. POLY-CH=CH(R1), wherein RI is as defined
above.
These terminally unsaturated interpolymers may be prepared by known
metallocene
chemistry and may also be prepared as described in U.S. Patent Nos. 5,498,809;
5,663,130; 5,705,577; 5,814,715; 6,022,929 and 6,030,930.
Another useful class of polymers is polymers prepared by cationic
polymerization
of isobutene, styrene, and the like. Common polymers from this class include
polyisobutenes obtained by polymerization of a C4 refinery stream having a
butene
content of about 35 to about 75 mass %, and an isobutene content of about 30
to about 60
mass %, in the presence of a Lewis acid catalyst, such as aluminum trichloride
or boron
trifluoride. A preferred source of monomer for making poly-n-butenes is
petroleum
feedstreams such as Raffinate II. These feedstocks are disclosed in the art
such as in U.S.
Patent No. 4,952,739. Polyisobutylene is a most preferred backbone of the
present
invention because it is readily available by cationic polymerization from
butene streams
(e.g., using A1C13 or BF3 catalysts). Such polyisobutylenes generally contain
residual
unsaturation in amounts of about one ethylenic double bond per polymer chain,
positioned along the chain. A preferred embodiment utilizes polyisobutylene
prepared
from a pure isobutylene stream or a Raffinate I stream to prepare reactive
isobutylene
polymers with terminal vinylidene olefins. Preferably, these polymers,
referred to as
highly reactive polyisobutylene (HR-PIB), have a terminal vinylidene content
of at least
65%, e.g., 70%, more preferably at least 80%, most preferably, at least 85%.
The
preparation of such polymers is described, for example, in U.S. Patent No.
4,152,499.
HR-PIB is known and HR-PIB is commercially available under the tradenames
GlissopalTM (from BASF) and UltravisTM (from BP-Amoco).
Polyisobutylene polymers that may be employed are generally based on a
hydrocarbon chain of from 400 to 3000. Methods for making polyisobutylene are
known.
Polyisobutylene can be functionalized by halogenation (e.g. chlorination), the
thermal
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"ene" reaction, or by free radical grafting using a catalyst (e.g. peroxide),
as described
below.
To produce (C) the hydrocarbon or polymer backbone may be functionalized,
with carboxylic anhydride-producing moieties selectively at sites of carbon-to-
carbon
unsaturation on the polymer or hydrocarbon chains, or randomly along chains
using any
of the three processes mentioned above or combinations thereof, in any
sequence.
Processes for reacting polymeric hydrocarbons with unsaturated carboxylic,
anhydrides and the preparation of derivatives from such compounds are
disclosed in U.S.
Patent Nos. 3,087,936; 3,172,892; 3,215,707; 3,231,587; 3,272,746; 3,275,554;
3,381,022; 3,442,808; 3,565,804; 3,912,764; 4,110,349; 4,234,435; 5,777,025;
5,891,953;
as well as EP 0 382 450 Bl; CA-1,335,895 and GB-A-1,440,219. The polymer or
hydrocarbon may be functionalized, with carboxylic acid anhydride moieties by
reacting
the polymer or hydrocarbon under conditions that result in the addition of
functional
moieties or agents, i.e., acid, anhydride, onto the polymer or hydrocarbon
chains
primarily at sites of carbon-to-carbon unsaturation (also referred to as
ethylenic or
olefinic unsaturation) using the halogen assisted functionalization (e.g.
chlorination)
process or the thermal "ene" reaction.
Selective functionalization can be accomplished by halogenating, e.g.,
chlorinating or brominating the unsaturated a-olefin polymer to about 1 to 8
mass %,
preferably 3 to 7 mass % chlorine, or bromine, based on the weight of polymer
or
hydrocarbon, by passing the chlorine or bromine through the polymer at a
temperature of
60 to 250 C, preferably 110 to 160 C, e.g., 120 to 140 C, for about 0.5 to 10,
preferably
1 to 7 hours. The halogenated polymer or hydrocarbon (hereinafter backbone) is
then
reacted with sufficient monounsaturated reactant capable of adding the
required number
of functional moieties to the backbone, e.g., monounsaturated carboxylic
reactant, at 100
to 250 C, usually about 180 C to 235 C, for about 0.5 to 10, e.g., 3 to 8
hours, such that
the product obtained will contain the desired number of moles of the
monounsaturated
carboxylic reactant per mole of the halogenated backbones. Alternatively, the
backbone
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and the monounsaturated carboxylic reactant are mixed and heated while adding
chlorine
to the hot material.
While chlorination normally helps increase the reactivity of stalling olefin
polymers with monounsaturated functionalizing reactant, it is not necessary
with some of
the polymers or hydrocarbons contemplated for use in the present invention,
particularly
those preferred polymers or hydrocarbons which possess a high terminal bond
content
and reactivity. Preferably, therefore, the backbone and the monounsaturated
functionality
reactant, (carboxylic reactant), are contacted at elevated temperature to
cause an initial
thermal "ene" reaction to take place. Ene reactions are known.
The hydrocarbon or polymer backbone can be functionalized by random
attachment of functional moieties along the polymer chains by a variety of
methods. For
example, the polymer, in solution or in solid form, may be grafted with the
monounsaturated carboxylic reactant, as described above, in the presence of a
free-radical
initiator. When performed in solution, the grafting takes place at an elevated
temperature
in the range of about 100 to 260 C, preferably 120 to 240 C. Preferably, free-
radical
initiated grafting would be accomplished in a mineral lubricating oil solution
containing,
e.g., 1 to 50 mass %, preferably 5 to 30 mass % polymer based on the initial
total oil
solution.
The free-radical initiators that may be used are peroxides, hydroperoxides,
and
azo compounds, preferably those that have a boiling point greater than about
100 C and
decompose thermally within the grafting temperature range to provide free-
radicals.
Representative of these free-radical initiators are azobutyronitrile, 2,5-
dimethylhex-3-
ene-2, 5-bis-tertiary-butyl peroxide and dicumene peroxide. The initiator,
when used,
typically is used in an amount of between 0.005% and 1% by weight based on the
weight
of the reaction mixture solution. Typically, the aforesaid monounsaturated
carboxylic
reactant material and free-radical initiator are used in a weight ratio range
of from about
1.0:1 to 30:1, preferably 3:1 to 6:1. The grafting is preferably carried out
in an inert
atmosphere, such as under nitrogen blanketing. The resulting grafted polymer
is
CA 02831948 2013-11-01
characterized by having carboxylic acid (or derivative) moieties randomly
attached along
the polymer chains: it being understood, of course, that some of the polymer
chains
remain ungrafted. The free radical grafting described above can be used for
the other
polymers and hydrocarbons of the present invention.
The preferred monounsaturated reactants that are used to functionalize the
backbone comprise mono- and dicarboxylic acid material, i.e., acid, or acid
derivative
material, including (i) monounsaturated C4 to C10 dicarboxylic acid wherein
(a) the
carboxyl groups are vicinyl, (i.e., located on adjacent carbon atoms) and (b)
at least one,
preferably both, of said adjacent carbon atoms are part of said mono
unsaturation; (ii)
derivatives of (i) such as anhydrides or C1 to C5 alcohol derived mono- or
diesters of (i);
(iii) monounsaturated C3 to C10 monocarboxylic acid wherein the carbon-carbon
double
bond is conjugated with the carboxy group, i.e., of the structure -C¨C-00-;
and (iv)
derivatives of (iii) such as C1 to C5 alcohol derived mono- or diesters of
(iii). Mixtures of
monounsaturated carboxylic materials (i) - (iv) also may be used. Upon
reaction with the
backbone, the monounsaturation of the monounsaturated carboxylic reactant
becomes
saturated. Thus, for example, maleic anhydride becomes backbone-substituted
succinic
anhydride, and acrylic acid becomes backbone-substituted propionic acid.
Exemplary of
such monounsaturated carboxylic reactants are fumaric acid, itaconic acid,
maleic acid,
maleic anhydride, chloromaleic acid, chloromaleic anhydride, acrylic acid,
methacrylic
acid, crotonic acid, cinnamic acid, and lower alkyl (e.g., C1 to C4 alkyl)
acid esters of the
foregoing, e.g., methyl maleate, ethyl fumarate, and methyl fumarate.
To provide the required functionality, the monounsaturated carboxylic
reactant,
preferably maleic anhydride, typically will be used in an amount ranging from
about
equimolar amount to about 100 mass % excess, preferably 5 to 50 mass % excess,
based
on the moles of polymer or hydrocarbon. Unreacted excess monounsaturated
carboxylic
reactant can be removed from the final dispersant product by, for example,
stripping,
usually under vacuum, if required.
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The alkylated phenol may be derived from cashew nut shell liquid (CNSL), such
as hydrogenated cardanol which predominantly contains 3-pentadecylphenol.
A characteristic structural feature of the alkyl phenol derived from CNSL is
meta
hydrocarbyl-substitution of the aromatic ring where the substituent is
attached to the ring
at its first (Cl) carbon atom. This structural feature is not available by
chemical alkyl
phenol synthesis such as the Friedel-Crafts reaction of phenol with olefins.
The latter
typically gives mixtures of ortho and para alkyl phenols (but only around 1 %
of meta
alkyl phenols), and where attachment of the alkyl group to the aromatic ring
is at the
second (C2) or higher carbon atom.
Cardanol, the product obtained by distilling technical CNSL, typically
contains 3-
pentadecylphenol (3 %); 3-(8-pentadecenyl) phenol (34-36 %); 3-(8, 11-
pentadecadienyl)
phenol (21-22 %); and 3-(8, 11, 14-pentadecatrienyl) phenol (40-41 %), plus a
small
amount of 5-(pentadecyl) resorcinol (c. 10 %), also referred to as cardol.
Technical
CNSL contains mainly cardanol plus some polymerized material.
Cardanol may
therefore be expressed as containing significant amounts of meta-linear
hydrocarbyl
substituted phenol, where the hydrocarbyl group has the formula C15H25-31 and
is
attached to the aromatic ring at its first carbon atom (C1).
Thus, both cardanol and technical CNSL contain significant quantities of
material
having long linear unsaturated side chains and only small quantities of
material with long
linear saturated side chains. The present invention may employ material where
a major
proportion, preferably all of the phenol, contains material with long linear
saturated side
chains. Such latter material is obtainable by hydrogenating cardanol; a
preferred example
is 3-(pentadecyl) phenol, where the pentadecyl group is linear and is attached
to the
aromatic ring at its first carbon atom. It may constitute 50 or more, 60 or
more, 70 or
more, 80 or more, or 90 or more, mass % of the additive of the invention. It
may contain
small quantities of 3-(pentadecyl) resorcinol.
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The alkylated phenol may be the product of the Friedel-Crafts alkylation of
phenol with a C14/C16/C1 8 mixture of linear alpha olefins (small levels of
other olefins
also present, e.g. C12 and C20). This produces a product that is highly C2
attached (alkyl
chain attached at 2nd carbon to the aromatic ring), with some C3 and higher
attachment
also seen. A mixture of ortho- and para- alkylated species (approximately 70%
to 30%)
are observed, along with around 10% dialkylated material.
The treat rate of additive (C) in the lubricating oil composition may for
example,
be 0.1 to 10, preferably 0.5 to 9, more preferably 1 to 8, mass %.
CO-ADDITIVES
The lubricating oil composition of the invention may comprise further
additives,
different from and additional to (B) and (C). Such additional additives may,
for example
include ashless dispersants, other metal detergents, anti-wear agents such as
zinc
dihydrocarbyl dithiophosphates, anti-oxidants and demulsifiers. In some cases,
an
ashless dispersant need not be provided.
It may be desirable, although not essential, to prepare one or more additive
packages or concentrates comprising the additives, whereby additives (B) and
(C) can be
added simultaneously to the base oil to form the lubricating oil composition.
Dissolution
of the additive package(s) into the lubricating oil may be facilitated by
solvents and by
mixing accompanied with mild heating, but this is not essential. The additive
package(s)
will typically be formulated to contain the additive(s) in proper amounts to
provide the
desired concentration, and/or to carry out the intended function in the final
formulation
when the additive package(s) is/are combined with a predetermined amount of
base
lubricant. Thus, additives (B) and (C), in accordance with the present
invention, may be
admixed with small amounts of base oil or other compatible solvents together
with other
desirable additives to form additive packages containing active ingredients in
an amount,
based on the additive package, of, for example, from 2.5 to 90, preferably
from 5 to 75,
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most preferably from 8 to 60, mass % of additives in the appropriate
proportions, the
remainder being base oil.
EXAMPLES
The present invention is illustrated by but in no way limited to the following
examples.
COMPONENTS
The following components were used:
Component (A):
(Al): an API Group II 600R basestock from Chevron
(A2): an API Group I basestock
Component (B):
(B1): a calcium salicylate detergent having a basicity index of 5.5.
Component (C):
(Cl) A polyisobutene succinic anhydride ("PIBSA") derived from a polyisobutene
of
number average molecular weight 950 (72% ai).
(C2) Hydrogenated cardenol ("CNSL" phenol)
(C3) Friedel-Crafts alkylated phenol ("SHOP" phenol)
HFO: a heavy fuel oil, ISO-F-RMK380
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SYSTEM LUBRICANTS
Selections of the above components were blended to give a range of system
lubricating oil compositions. Some of the lubricants are examples of the
invention and
others are reference examples for comparison purposes. The compositions of the
lubricants tested are shown in the tables below under the "RESULTS" heading.
TESTING
Light Scattering
Test lubricants were evaluated for asphaltene dispersancy using light
scattering
according to the Focused Beam Reflectance Method ("FBRM"), which predicts
asphaltene agglomeration.
The FBRM test method was disclosed at the 7th International Symposium on
Marine Engineering, Tokyo, 24th - 28th October 2005, and was published in 'The
Benefits
of Salicylate Detergents in TPEO Applications with a Variety of Base Stocks',
in the
Conference Proceedings. Further details were disclosed at the CIMAC Congress,
Vienna, 21st -24th May 2007 and published in "Meeting the Challenge of New
Base
Fluids for the Lubrication of Medium Speed Marine Engines ¨ An Additive
Approach" in
the Congress Proceedings. In the latter paper it is disclosed that by using
the FBRM
method it is possible to obtain quantitative results for asphaltene
dispersancy that predict
performance for lubricant systems based on base stocks containing greater than
or less
than 90% saturates, and greater than or less than 0.03% sulphur. The
predictions of
relative performance obtained from FBRM were confirmed by engine tests in
marine
diesel engines.
The FBRM probe contains fibre optic cables through which laser light travels
to
reach the probe tip. At the tip, an optic focuses the laser light to a small
spot. The optic
is rotated so that the focussed beam scans a circular path between the window
of the
CA 02831948 2013-11-01
probe and the sample. As particles flow past the window they intersect the
scanning
path, giving backscattered light from the individual particles.
The scanning laser beam travels much faster than the particles; this means
that the
particles are effectively stationary. As the focussed beam reaches one edge of
the particle
there is an increase in the amount of backscattered light; the amount will
decrease when
the focussed beam reaches the other edge of the particle.
The instrument measures the time of the increased backscatter. The time period
of
backscatter from one particle is multiplied by the scan speed and the result
is a distance
or chord length. A chord length is a straight line between any two points on
the edge of a
particle. This is represented as a chord length distribution, a graph of
numbers of chord
lengths (particles) measured as a function of the chord length dimensions in
microns. As
the measurements are performed in real time the statistics of a distribution
can be
calculated and tracked. FBRM typically measures tens of thousands of chords
per
second, resulting in a robust number-by-chord length distribution. The method
gives an
absolute measure of the particle size distribution of the asphaltene
particles.
The Focused beam Reflectance Probe (FBRM), model Lasentec D600L, was
supplied by Mettler Toledo, Leicester, UK. The instrument was used in a
configuration
to give a particle size resolution of 1 1.tm to 1 mm. Data from FBRM can be
presented in
several ways. Studies have suggested that the average counts per second can be
used as a
quantitative determination of asphaltene dispersancy. This value is a function
of both the
average size and level of agglomerate. In this application, the average count
rate (over
the entire size range) was monitored using a measurement time of one minute
per reading
over 30 minutes.
The test lubricant formulations were heated to 60 C and stirred at 400rpm;
when
the temperature reached 60 C the FBRM probe was inserted into the sample and
measurements made for 30 minutes. An aliquot of heavy fuel oil (10% w/w) was
introduced into the lubricant formulation under stirring using a four blade
stirrer (at 400
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=
rpm). A value for the average counts per second was taken when the count rate
had
reached an equilibrium value.
RESULTS
The results of the FBRM tests are summarised in the tables below, where lower
particle count values indicate better performance.
TABLE 1
Three system lubricants contained a zinc-containing dispersant booster with
0.5 %
nitrogen and 0.95 % zinc, and 10 % HFO. The lubricants also contained the
salicylate
detergent (B1) at a treat rate of 3.8%. One lubricant comprised a Group I
basestock and
no PIBSA; the second lubricant comprised a Group II basestock and no PIBSA;
the third
lubricant comprised a Group II basestock and PIBSA (C) at a treat rate of 7 %.
GROUP I (Al) GROUP II (A2) GROUP II + PIBSA
26,431 39,032 14,812
The numbers are particulate counts.
The results show that, in Group II oil, salicylate gives an inferior
performance
than its use in Group I oil. However, the right-hand column shows that
addition of
PIBSA significantly improves the performance of salicylate to the extent that
it is better
than the Group I salicylate-containing lubricant.
TABLE 2
A set of system lubricants, of 5 BN, comprised a Group II basestock (Al) and a
salicylate package (B1) at a treat rate of 2%. PIBSA, CNSL phenol and SHOP
phenol
were either absent or present in different amounts as indicated.
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Mass % PIBSA "CNSL" "SHOP"
Particle Count(s) Particle Counts Particle Counts
7, 160 7, 160 7, 160
2 1,621 5,944 6,241
4 831 1,329 4,757
6 454 28 1,770
8 366 77 317
The results show that improvement occurs at the lowest treat rate of 2 % and
that
further improvement is possible at higher treat rates. It should be noted
that, at higher
treat rates, viscosity may be increased.
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